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Publication numberUS5597514 A
Publication typeGrant
Application numberUS 08/377,761
Publication dateJan 28, 1997
Filing dateJan 24, 1995
Priority dateJan 24, 1995
Fee statusPaid
Publication number08377761, 377761, US 5597514 A, US 5597514A, US-A-5597514, US5597514 A, US5597514A
InventorsBoris A. Miksic, Christophe Chandler, Margarita Kharshan, Alla Furman, Barry Rudman, Larry Gelner
Original AssigneeCortec Corporation
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Corrosion inhibitor for reducing corrosion in metallic concrete reinforcements
US 5597514 A
Abstract
A corrosion inhibitor formulation for use in reinforced concrete structures, the inhibitor reducing the rate of corrosion in metallic reinforcing rods placed within the structures. The formulation comprises a mixture of benzoic acid, aldonic acid, and a triazole such as benzotriazole or tolyltriazole.
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Claims(5)
What is claimed is:
1. A corrosion inhibitor for reducing corrosion of metallic reinforcement embedded in situ within poured concrete structures comprising a mixture of the following formulation:
(a) a benzoic acid component selected from the group consisting of water soluble salts of benzoic acid and benzoic acid in the range of from between about 8% to 12% by weight;
(b) an aldonic acid component selected from the group consisting of aldonic acid and its water soluble salts in the range of from between about 34% to 36% by weight;
(c) water in the range of from between about 52% to 58%;
(d) a triazole selected from the group consisting of benzotriazole, tolyltriazole and their water soluble salts in the range of up to 1% by weight; and
(e) wherein the formulation is provided in an admixture with raw concrete prior to pouring and curing in an amount ranging from between about 8 ounces and 48 ounces per cubic yard of raw cement.
2. The formulation of claim 1 wherein the admixture is in an amount of 16 ounces per cubic yard of raw concrete.
3. The formulation of claim 1 wherein the triazole component is present in an amount of 0.5%.
4. A corrosion inhibitor for reducing corrosion of metallic reinforcement embedded in situ within poured concrete structures comprising a mixture of the following formulation:
(a) a benzoic acid component selected from the group consisting of water soluble salts of benzoic acid and benzoic acid in an amount of 10% by weight;
(b) an aldonic acid component selected from the group consisting of aldonic acid and its water soluble salts in an amount of 35% by weight;
(c) water in an amount of 55% by weight;
(d) a triazole selected from the group consisting of benzotriazole, tolyltriazole and their water soluble salts in the range of up to 1% by weight; and
(e) wherein the formulation is provided in an admixture with raw concrete prior to pouring and curing in an amount ranging from between about 6 ounces and 10 ounces per cubic yard of raw concrete.
5. The method of inhibiting the corrosion of metallic reinforcements embedded in situ within poured concrete structures which comprises providing, in admixture with raw concrete prior to pouring and curing of the raw concrete, a compound of the following formulation:
(a) a benzoic acid component selected from the group consisting of water soluble salts of benzoic acid and benzoic acid in the range of from between about 8% to 12% by weight;
(b) an aldonic acid component selected from the group consisting of aldonic acid and its water soluble salts in the range of from between about 34% to 36% by weight;
(c) water in the range of from between about 52% to 58%;
(d) a triazole selected from the group consisting of benzotriazole, tolyltriazole and their water soluble salts in the range of up to 1% by weight; and
(e) with the formulation being present in the raw concrete prior to pouring in an amount ranging from between about 8 ounces and 48 ounces per cubic yard of said raw concrete.
Description
BACKGROUND OF THE INVENTION

The present invention relates generally to corrosion inhibitors for use in reinforced concrete structures, and more particularly to corrosion inhibitors for reducing the rate of corrosion in metallic reinforcing rods placed within structures formed of concrete. The present inhibitor is designed for use in admixture with raw concrete, and hence is provided on an in-situ basis within the concrete mixing.

Concrete structures such as highways and bridges typically utilize metallic reinforcement members embedded therewithin to provide stability and additional strength to the concrete, and to enhance the ability of the concrete to withstand shear forces. These reinforcements are typically in the form of reinforcing rods, wire mesh, metallic fibers, and the like, and are usually situated in regular intervals within the cured concrete by pouring raw or uncured concrete therearound or, in the case of metallic fibers, added during the concrete mixing operation, for subsequent curing. The term "raw concrete" is utilized in a comprehensive sense, and is intended to relate to wet workable concrete mixtures which have not yet cured to their solid form. Upon the passage of time, the metallic reinforcements have a tendency to corrode as external elements such as moisture, atmospheric pollutants such as carbon dioxide, oxides of sulfur, oxides of nitrogen, hydrogen sulfide road treatment chemicals permeate through the concrete structure and reach the metal. When utilized in highways, bridges, and parking structures, chlorides including sodium chloride and calcium chloride may permeate the concrete structure due to the widespread utilization of such materials as a mechanism to melt ice and snow from the road surfaces. Both calcium chloride and sodium chloride are widely used for this purpose.

In order to facilitate the access of inhibitors to concrete reinforcements, including particularly the surfaces of concrete reinforcements, it is desirable that corrosion inhibitors be added to the raw concrete mixture in order to provide for contact with the surfaces of the metallic reinforcement members or structures. The corrosion inhibitor added in this fashion normally migrates at a rate sufficient to provide ongoing protection over relatively extended periods of time, and hence have an ability to protect the metallic reinforcements over such a period of time. It is, of course, always possible to boost the effectiveness of the inhibitor on a post-cure basis, provided the inhibitor can be placed within the body of the concrete.

In accordance with the present invention, a formulation has been developed which is readily adapted for use in admixture with raw or wet concrete mixtures, and which provides long-lasting and reliable corrosion inhibiting properties for metallic reinforcements. The formulation of the present invention facilitates the inhibition of corrosion while, at the same time, not adversely impacting or affecting the curing rate or ultimate strength of the concrete in which it is added.

Therefore, it is a primary object of the present invention to provide an improved in-situ corrosion inhibitor designed for admixture with raw or wet concrete mixtures, in which metallic reinforcements are placed.

It is a further object of the present invention to provide an improved formulation for use in admixture with raw or wet concrete mixtures wherein the formulation provides protection for the metallic reinforcements without adversely affecting the curing rate or ultimate strength of the concrete.

Other and further objects of the present invention will become apparent to those skilled in the art upon a study of the following specification and appended claims.

SUMMARY OF THE INVENTION

By way of summary, the present invention utilizes a mixture which is designed for use in admixture with raw or wet concrete, and wherein the formulation for the mixture employs a corrosion inhibitor having the formula: ##STR1## where "n" is an integer having a value of 6 or 7 including its water soluble salts, in an amount sufficient to hinder corrosion, and water soluble salts of benzoic or substituted benzoic acid, together with an amount of benzotriazole and/or tolyltriazole, and/or their water soluble salts, the triazole compounds being optionally included for certain applications. While the incorporation of certain glucose substances in concrete may retard the rate of curing, their concentration level of the formulations of the present invention is sufficiently low so that no adverse affects occur upon curing.

Typically, the mixtures of the present invention comprise a mixture of water soluble salts of benzoic or substituted benzoic acid in an amount ranging from 8% to 12%, an aldonic acid having the formula: ##STR2## where "n" is an integer having a value of 6 or 7 including its water soluble salts, in an amount effective to hinder corrosion in an amount ranging from between 34% and 36%, water in an amount ranging from between 52% and 58%, and up to 1% of a triazole selected from the group consisting of tolyltriazole, benzotriazole, and their water soluble salts. The term "water soluble salts" in connection with aldonic acid and the listed triazoles typically include sodium, potassium, and ammonium derivatives. Benzotriazole, for example, forms stable metallic salts which are water soluble. These triazole compounds are particularly desirable when copper or copper alloys are embedded or otherwise in contact with the cured concrete. In accordance with the present invention, it has been found that the formulation of the present invention is provided in admixture to the raw concrete in an amount ranging from between 8 ounces and ounces per cubic yard of wet concrete. This typically ranges from between 16 ounces and 40 ounces. The corrosion inhibiting mixture of the present invention is typically added during mixing and blending of the raw concrete, and may be undertaken without difficulty during virtually any point in the mixing process, the only requirement being, of course, that the inhibitor becomes reasonably uniformly blended prior to pouring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the preferred embodiment of the present invention, a corrosion inhibitor for reducing corrosion in reinforcement materials within concrete consists of a mixture having the following general formulation:

______________________________________Component            Percentage by Weight______________________________________Water soluble salts of benzoic and                 8%-12%substituted benzoic acidAldonic acid or its water soluble salts                34%-36%Water                52%-58%Benzotriazole, tolyltriazole including                up to 1%.their water soluble salts______________________________________

In admixture, the selected formulation is mixed within raw concrete in an amount ranging from between about 8 ounces and 48 ounces per cubic yard of raw concrete. The present invention may be practiced in accordance with the following preferred examples.

EXAMPLE I

A corrosion inhibiting mixture was prepared in accordance with the following formulation:

______________________________________Component        Percentage by Weight______________________________________Ammonium benzoate            10%Sodium glucoheptonate            35%Water            55%Benzotriazole    trace, less than 1%.______________________________________

This formulation was provided in admixture with concrete in an amount of 8 ounces by weight per cubic yard of concrete for inhibiting the corrosion of metallic reinforcements.

EXAMPLE II

A corrosion inhibiting mixture was prepared in accordance with the following formulation:

______________________________________Component        Percentage by Weight______________________________________Ammonium benzoate             8%Sodium glucoheptonate            36%Water            56%Benzotriazole    trace, less than 1%.______________________________________

This formulation was provided in admixture with concrete in an amount of 16 ounces per cubic yard raw concrete for inhibiting the corrosion of metallic reinforcements.

EXAMPLE III

A corrosion inhibiting mixture was prepared in accordance with the following formulation:

______________________________________Component        Percentage by Weight______________________________________Ammonium benzoate            12%Sodium glucoheptonate            34%Water            53%Benzotriazole      1%.______________________________________

This formulation was provided in admixture with concrete in an amount of 32 ounces per cubic yard of raw concrete for inhibiting the corrosion of metallic reinforcements.

EXAMPLE IV

A corrosion inhibiting mixture was prepared in accordance with the following formulation:

______________________________________Component        Percentage by Weight______________________________________Ammonium benzoate             9%Sodium glucoheptonate            35%Water            55%Benzotriazole      1%.______________________________________

This formulation was provided in admixture with concrete in an amount of 48 ounces per cubic yard of raw concrete for inhibiting the corrosion of metallic reinforcements.

GENERAL DISCUSSION

As has been indicated, the utilization of the formulations based upon mixtures in accordance with the present invention enhance the lifetime of metallic reinforcements so as to preserve the integrity of concrete structures, particularly highways, bridges and automobile parking facilities. The widespread utilization of chloride-containing salts such as sodium chloride and calcium chloride, while necessary for safety purposes, have been detrimental to the integrity of reinforced concrete structures. Automobiles carry certain residual amounts of these chloride-containing materials onto areas which are not normally exposed, but which nevertheless are adversely affected by relatively rapid deterioration of the metallic reinforcements.

Reinforced concrete structures are typically provided with steel bars and/or rods for longitudinal tension reinforcement as well as compression reinforcement, and reinforcement against diagonal tension. Expanded metal, steel-wire mesh, hoop iron or other thin rods may be embedded in the concrete structure for reinforcement purposes. Being ferrous-based materials, and as indicated hereinabove, the integrity of the reinforcement is subject to deterioration whenever exposure to chloride-containing salts, oxides of sulfur or nitrogen are encountered. When mixtures containing the formulations of the present invention are utilized in the concrete on an in-situ basis, significant protection of the reinforcement is obtained.

To enhance mixing of the formulation of the present invention with wet or raw concrete, it is sometimes desirable to blend the formulation with an inert carrier in order to enhance the dispersion of the formulation within the wet concrete. Inert carriers for blending into wet concrete are, of course, well known, with silica powder being one of many examples.

It will be appreciated that various modifications may be made in the present invention, and that the formulations provided hereinabove are deemed representative only and are not to be deemed limiting for the true spirit and scope of the invention.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2941953 *Jul 27, 1956Jun 21, 1960Hagan Chemicals & Controls IncMethod of inhibiting corrosion of copper and cuprous alloys in contact with water
US3537869 *Sep 7, 1967Nov 3, 1970Proell Wayne AAdditive for cementitious mixtures
US3589859 *Oct 9, 1967Jun 29, 1971Exxon Research Engineering CoGluconate salt inhibitors
US3726817 *Nov 3, 1971Apr 10, 1973D NiswongerSurface coating compositions comprising polyester resin,wax and flock and coatings thereof
US3748159 *Apr 20, 1972Jul 24, 1973Halliburton CoHigh temperature cementing compositions containing a lignosulfonic acid salt and a pentaboric acid salt
US3751387 *Apr 13, 1971Aug 7, 1973Chemtree CorpSelf-supporting structures for nuclear radiation shields and binders therefor
US3789051 *Sep 23, 1971Jan 29, 1974Du PontReinforced resin compositions
US3852213 *Jan 12, 1972Dec 3, 1974Gaf CorpChelating compositions and detergent compositions pertaining to same
US4242214 *Oct 17, 1979Dec 30, 1980Texaco Development CorporationAlcohol and tetraborate, metaborate, metasilicate, benzoate, tolyl-or benzotriazole
US4315889 *Dec 26, 1979Feb 16, 1982Ashland Oil, Inc.Method of reducing leaching of cobalt from metal working tools containing tungsten carbide particles bonded by cobalt
US4337094 *May 11, 1981Jun 29, 1982The Euclid Chemical CompanyAdditive composition for Portland cement materials
US4391645 *Apr 12, 1982Jul 5, 1983Diamond Shamrock CorporationAromatic sulfonic acid formaldehyde condensates and aromatic hydroxy compounds
US4402847 *May 19, 1982Sep 6, 1983Basf Wyandotte CorporationHigh lead solder corrosion inhibitors
US4410367 *Jun 10, 1982Oct 18, 1983General Electric Co.Method for treating aggregate and products obtained therefrom
US4512915 *Aug 24, 1982Apr 23, 1985Roquette FreresComposition and method of inhibiting corrosion by water of metal substrates
US4642137 *Mar 6, 1985Feb 10, 1987Lone Star Industries, Inc.Portland cements
US4662942 *Sep 20, 1985May 5, 1987Idemitsu Petrochemical Co., Ltd.Saponified sulfonated styrene-maleic acid copolymer as fluidizing additive
US4693829 *Apr 3, 1986Sep 15, 1987Calgon CorporationUse of carboxylic acid/sulfonic acid copolymers as aluminum ion stabilizers
US4746367 *Dec 17, 1986May 24, 1988The Dow Chemical CompanySuperplasticizer composition for use with hydraulic cements
US4758363 *Nov 2, 1987Jul 19, 1988Texaco Inc.Oxidation and corrosion resistant diesel engine lubricant
US4759864 *Sep 4, 1987Jul 26, 1988Texaco Inc. & S.A. Texaco Petro, N.V.Water soluble liquid alcohol freezing point depressant, aliphatic mobobasic acid or alkali metal salt, alkali metal borates and hydrocarbyl triazole
US4975219 *Jan 10, 1989Dec 4, 1990Kurita Water Industries, Ltd.Comprising tannic acid and/or a salt, sugar, at least one member selected form aldonic acids of hexoses or salts and aldonic acid of heptose or salts; nontoxic
US4990191 *Feb 21, 1989Feb 5, 1991Westvaco CorporationSlurry also contains formaldehde-naphalene sulfonate condensate, or inorganic salts
US4997484 *Jun 5, 1990Mar 5, 1991Lone Star Industries, Inc.Fly ash, citric acid, alkali metal compound
US5039454 *May 17, 1990Aug 13, 1991Policastro Peter PZinc-containing magnesium oxychloride cements providing fire resistance and an extended pot-life
US5104562 *Aug 3, 1990Apr 14, 1992Eszakmagyarorszagi VegyimuvekGlycol-free; urea; optionally a small quantity of glycol; freezes without expansion; environmentally safe; anti-freeze
US5244600 *Mar 2, 1992Sep 14, 1993W. R. Grace & Co.-Conn.Glucoheptonic acid
US5326529 *May 24, 1993Jul 5, 1994Cortec CorporationCylinders
Non-Patent Citations
Reference
1 *CS 261986, May 15, 1989, Chemical Abstract 112:101304 only.
2 *EP 652305, May 10, 1995, Chemical Abstract 123:15551 only.
3 *JP 0149362 Sep. 14, 1982, Derwent Abstract 89637 E/92 only.
4 *JP 0149362 Sep. 14, 1982, Derwent Abstract 89637E/92 only.
5 *JP 54024937 Feb. 24, 1979, Chemical Abstract 91:8809 only.
6 *JP 54126229 Oct. 1, 1979, Chemical Abstract 92:63581 only.
7 *JP 56125259, Nov. 1, 1981, Chemical Abstract 96:56943 only.
8 *JP 56125267 Oct. 1, 1981, Chemical Abstract 96:39853 only.
9 *JP 60067681 Apr. 18, 1985, Chemical Abstract 103:57548 only.
10 *Mater. Perform. (1983), 22 (6), 13 16, Chemical Abstract 99:93449 only.
11Mater. Perform. (1983), 22 (6), 13-16, Chemical Abstract 99:93449 only.
12 *SU 1689329, Nov. 7, 1991, Chemical Abstract 122:10038 only.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5756003 *Feb 4, 1997May 26, 1998Solvay Deutschland GmbhContacting metal with the composition
US6174461Jun 29, 1999Jan 16, 2001Cortec CorporationConcrete sealers with migrating corrosion inhibitors
US6265667Jan 14, 1998Jul 24, 2001Belden Wire & Cable CompanyAnticorrosion coating containing formaldehyde and((di-(2-hydroxyethyl)amino)methyl)ar-methyl-1-h-benzotriazo le
US6306210Aug 31, 2000Oct 23, 2001Cortec CorporationCorrosion inhibitor container
US6340438Apr 19, 1999Jan 22, 2002Tomahawk, Inc.Corrosion inhibiting admixture for concrete
US6342101Oct 11, 1999Jan 29, 2002Cortec CorporationMigrating corrosion inhibitors combined with concrete and modifers
US6551552Sep 27, 2000Apr 22, 2003Cor/Sci LlcComprises gas impermeable enclosure comprising shell adapted to maintain pressure differences with exterior containing desiccant, corrosion inhibitor, and/or inert gas; storage stability
US6610138 *Nov 13, 2001Aug 26, 2003Paul W. BrownMethod of resisting corrosion in metal reinforcing elements contained in concrete and related compounds and structures
US6732482Nov 7, 2002May 11, 2004Paul W. BrownMethod of resisting corrosion in metal reinforcing elements contained in concrete and related compounds and structures
US6907708 *Dec 8, 2000Jun 21, 2005James Hardie International FinanceLightweight wall construction
US6982062Jul 22, 2003Jan 3, 2006Ashland Inc.Corrosion inhibiting composition
US7048873 *Mar 20, 2002May 23, 2006Cortec CorporationComposition and method for repairing metal reinforced concrete structures
US7118615 *Sep 12, 2003Oct 10, 2006Cortec CorporationBiodegradable corrosion inhibitor composition
US7125441Feb 17, 2005Oct 24, 2006Cortec CorporationCorrosion inhibiting materials for reducing corrosion in metallic concrete reinforcements
US7264707Sep 30, 2005Sep 4, 2007Cortec CorporationCorrosion inhibitor materials for use in combination with cathodic protectors in metallic structures
US7297191Oct 6, 2006Nov 20, 2007Cortec CorporationBiodegradable corrosion inhibitor composition
US7541089 *Dec 10, 2002Jun 2, 2009Cortec CorporationComposition and method for preserving posttensioning cables in metal reinforced concrete structures
US7871695Dec 16, 2005Jan 18, 2011NV Bakaert SAReinforced structure comprising a cementitious matrix and zinc coated metal elements
US7892601Nov 14, 2006Feb 22, 2011Cortec CorporationCorrosion inhibiting powders and processes employing powders
US8236204Mar 11, 2011Aug 7, 2012Wincom, Inc.Corrosion inhibitor compositions comprising tetrahydrobenzotriazoles solubilized in activating solvents and methods for using same
US8236205Mar 11, 2011Aug 7, 2012Wincom, Inc.Corrosion inhibitor compositions comprising tetrahydrobenzotriazoles and other triazoles and methods for using same
US8336285 *Dec 9, 2009Dec 25, 2012Nv Bekaert SaCord for reinforcement of a cementitious matrix
US8535567Aug 3, 2012Sep 17, 2013Wincom, Inc.Corrosion inhibitor compositions comprising tetrahydrobenzotriazoles solubilized in activating solvents and methods for using same
US8535568Aug 3, 2012Sep 17, 2013Wincom, Inc.Corrosion inhibitor compositions comprising tetrahydrobenzotriazoles solubilized in activating solvents and methods for using same
US8535569Aug 3, 2012Sep 17, 2013Wincom, Inc.Corrosion inhibitor compositions comprising tetrahydrobenzotriazoles and other triazoles and methods for using same
US8603603Feb 7, 2011Dec 10, 2013Cortec CorporationCorrosion inhibiting systems
US8722592Jul 25, 2008May 13, 2014Wincom, Inc.Use of triazoles in reducing cobalt leaching from cobalt-containing metal working tools
US8800224Aug 30, 2010Aug 12, 2014Cortec CorporationCorrosion inhibiting vapor for use in connection with encased articles
US20110239905 *Dec 9, 2009Oct 6, 2011Nv Bekaert Sacord for reinforcement of a cementitious matrix
WO2006067095A1 *Dec 16, 2005Jun 29, 2006Bekaert Sa NvReinforced structure comprising a cementitious matrix and zinc coated metal elements
Classifications
U.S. Classification252/390, 252/389.62, 106/808, 106/692, 106/819, 252/387, 422/16, 106/14.14, 106/713, 106/14.16, 106/690, 422/7, 422/17, 106/728, 106/14.17, 106/727, 106/14.13, 106/816, 252/394, 252/396
International ClassificationC04B22/08, C04B28/02, C04B24/06
Cooperative ClassificationC04B28/02, C04B24/06, C04B2103/61, C04B22/08
European ClassificationC04B22/08, C04B28/02, C04B24/06
Legal Events
DateCodeEventDescription
May 13, 2008FPAYFee payment
Year of fee payment: 12
May 24, 2004FPAYFee payment
Year of fee payment: 8
Feb 3, 2000FPAYFee payment
Year of fee payment: 4
Jan 24, 1995ASAssignment
Owner name: CORTEC CORPORATION, MINNESOTA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MIKSIC, BORIS A.;CHANDLER, CHRISTOPHE;KHARSHAN, MARGARITA;AND OTHERS;REEL/FRAME:007330/0261
Effective date: 19950116